Device for the individual adjustment of the striking force in a typewriter

ABSTRACT

An adjusting spring is associated with each type bar acting as a function of the movement, so as to increase, maintain or reduce the striking force. Each of the springs is attached by one of its ends to a movable element of the actuating system of the corresponding type bar and by its other end to anchoring means at an adjustable position of a member movable as a function of the movement. The movable member is an elongated part capable of pivoting around an axis parallel to the platen of the machine, capable of taking up two positions corresponding to the lower case and upper case positions respectively of the movement. The movable member has a U-shaped section and its surface has series of slots corresponding in number to the number of type bars, each slot having a series of notches forming fixing points for the adjusting springs.

United States Patent [191 Costa Jan. 22, 1974 1 DEVICE FOR THE INDIVIDUAL 3,393,786 7/1968 Heidt 197 17 DJU E OF H STRIKING FORCE 3,229,798 1/1966 Grashoff 197/17 [75] Inventor: Georges Costa, Yverdon,

Switzerland [73] Assignee: Paillard S.A., Sainte Croix Vaud,

Switzerland [22] Filed: Dec. 1, 1971 [21] Appl. No.: 203,716

[30] Foreign Application Priority Data Dec. 15, 1970 Switzerland 18599/70 [52] US. Cl. 197/17 [51] Int. Cl B41j 23/08 [58] Field of Search 197/17, 33

[5 6] References Cited UNITED STATES PATENTS 2,890,782 6/1959 Stuiber 197/33 3,458,024 7/1969 Schaefer.... 2,226,924 12/1940 Dobson 3,011,616 12/1961 Scribner 197/17 Z2 29 a; I 25 IN A TYPEWRITER Primary Examiner-Robert E. Pulfrey Assistant Examiner-R. T. Rader Attorney, Agent, or FirmEmory L. Groff et al.

[5 7] ABSTRACT An adjusting spring is associated with eachtype bar acting as a function of the movement, so as to increase, maintain or reduce the striking force. Each of the springs is attached by one of its ends to a movable element of the actuating system of the corresponding type bar and by its other end to anchoring means at an adjustable position of a member movable as a function of the movement. The movable member is an elongated part capable of pivoting around an axis parallel to the platen of the machine, capable of taking up two positions corresponding to the lower case and upper case positions respectively of the movement. The movable member has a U-shaped section and its surface has series of slots corresponding in number to the number of type bars, each slot having a series of notches forming fixing points for the adjusting springs.

1 Claim, 5 Drawing Figures PATENTH] JAN 22 I974 sum 1 or 2 INVENTOR GEOEGES @0574 ATTORNEY DEVICE FOR THE INDIVIDUAL ADJUSTMENT OF THE STRIKING FORCE IN A TYPEWRITER The invention relates to a device for individual adjustment of the striking force of each type bar of a typewriter acting as a function of the movement, so as to increase, maintain or reduce this striking force, and comprising an adjusting spring associated with each type bar.

By device for individual adjustment is meant a mechanism enabling adjustment of the striking force of each type bar.

It is an object of the invention to provide means enabling the production, on a typed page, of an impression of identical intensity, whatever the size of the characters upper or lower case borne by the type bars. This result is obtained when the speed with which a character strikes the paper corresponds to the useful surface of each character. Consequently it involves adjustment of the speed in order to obtain a variable striking force adapted to each character.

In known types of electrical typewriters, the adjustment is effected by means of adjustable stops, mostly constituted by screws. Generally, these devices are complicated due to the fact that two different mechanisms are provided, used to adjust the striking force applied to the type bars, according as a capital letter or a small letter is involved. There are also known adjusting devices comprising braking springs for the movement of the type bars, the springs being displaceable with said movement.

It is an object of the present invention to provide a simpler solution for the individual adjustment of the striking force.

According to the invention, there is provided a device of the aforesaid type, characterized in that each of these springs is attached by one of its ends to a movable element of the corresponding actuating system of the type bar and by its other end to anchoring means adjustable in position on a member movable as a function of the movement.

The accompanying drawing shows, diagrammatically and purely by way of illustrative but non-limiting example, one embodiment of a device according to the invention.

In the drawing:

FIG. 1 is a side view, in partial section, of an embodiment of an adjusting device according to the invention;

FIG. 2 is a rear view of a portion of FIG. 1; and

FIGS. 3 to 5 illustrate diagrammatically various operational positions of the adjusting device.

The device shown in FIGS. 1 and 2 comprises a type bar 1 pivoting around a rod 2 mounted on a segment 3. The type bar 1 is actuated in known manner (described. for example, in co-pending US. Pat. application No. 203,515); pivoting around a rod 27 mounted on a cross-member 28 of the frame of the typewriter. This actuating lever 26 has a guide orifice 29 for a pin 30 rigidly fixed to an intermediate lever 31 hinged at 310. The latter is connected to the type bar 1 through a pull rod 32. The platen of the machine, indicated diagrammatically at 35, pivots around an axle 36.

The segment 3 is fixed to a plate 4 capable of sliding, through balls 5, on guides 6 rigidly fixed to the two plates 7, 8, which form part of the frame of the machine. The segment 3, as is usual in typewriters, can occupy two positions: a position 3 called high position,

illustrated in solid lines in FIG. 1 and corresponding to the striking of lower case or small letters; a position 3" called low position, illustrated partly in discontinuous lines and corresponding to the striking of upper case or capital letters. The passage from one to the other of these two positions is actuated by a lever 9 pivoted at 10 on the plate 7. One of the arms of the lever 9 bears a pin 11 which is engaged in a fork l2 rigidly fixed to the plate 4. The lever 9 is actuated by an arm 13 hinged at 14 and actuated in known manner by a movement key, not shown, situated on the keyboard of the typewriter.

Another arm 15, hinged at 16 on the lever 9, transmits the movement of the latter to a part 17, of U- shaped section and extending parallel to the keyboard of the machine. The part 17 is riveted at its two ends to two plates 18 and 19. These plates bear pivots respectively 20 and 21 defining an axis X X parallel to the axle 36 of the platen 35, around which the part 17 can pivot. The arm 15 is hinged at 22 on the plate 18. It is seen that due to this hinged assembly, the plate 18 is brought into an angular position 18', shown in full lines in FIG. 1, when the segment 3 occupies high position 3', and in another angular position 18", shown in broken lines in FIG. 1, when the segment 3 occupies the low position 3". In this way, at these two angular positions 18', 18" of the plate 18 there correspond two particular positions of the part 17.

The part 17 has, on the concave section of the U, a series of slots 23, 23 23 equal in number to the number of type bars. Each slot is provided with a series of notches 24 forming a series of points of attachment for one end 33 of a return spring 25 for the actuating lever 26 of each type bar 1. This return spring 25 is fixed at its other end at a point 34 provided on the actuating lever 26.

It will be seen that by means of each return spring 25 corresponding to a certain type bar 1, it is possible to adjust the actuating force applied to the type bar concerned by moving the free end 33 of the spring and by fixing it in a selected notch 24, provided in the slot 23.

The return springs 25 act during the free stroke of each type bar, before the striking thereof. According to their force,'they determine the speed with which the character concerned hits the paper, said speed corresponding to the useful surface of each character. Due to the fact that the two characters of a same type bar can have two very different useful surfaces, it is necessary to adjust the return force of the type bar concerned as a function of the movement, that is to say as a function of the high and low positions of the segment 3. I

It will be seen that the device described enables such adjustment to be effected in a simple manner, as illustrated in FIGS. 3 to 5. In these figures, the spring 25, shown diagrammatically in mixed lines, is anchored, by its free end, at a variable point of attachment 33 selected along a slot 23 of the movable part 17 around the pivot 20 (of axis X X, perpendicular to the plane of the figure) and taking the positions 17' and 17" corresponding respectively to the high 3' and low 3" positions of the segment 3. The spring 25 has a variable length 1', l" as a function of position 17, 17" of the part 17, which length corresponds to a certain return force for each of these positions.

In FIG. 3, the spring 25 is anchored at a point of attachment situated substantially at the middle of the concave portion of the U of the part 17. Under these conditions, 1' 1", so that the return force does not vary between the two positions 17' and 17" of the part 17.

In FIG. 4, the free end of the spring 25 is displaced to a point of attachment occuring towards the top of the concave portion of the U of the part 17. Under these conditions, 1 1", since the point of attachment is closer to the point 34 in the position 17' than in the position 17". As a result, the return force of the spring 25 is higher, and conjointly the striking force is weaker, in the position 17" corresponding to small letters.

In FIG. 5, the free end of the spring 25 is displaced on the other hand to a point of attachment occurring towards the bottom of the concave portion of the U of the part 17. It is clear that under these conditions, the striking force varies in inverse sense to 'the preceding case, since 1' 1'', that is to say the striking force is greater in position 17" (capital letters) than in position 17 (small letters).

I claim:

1. An individual adjusting device for the striking force of each type bar of a typewriter acting as a function of the position of the lower case and upper case movement, so as to increase, maintain constant or reduce said striking force, each type bar including an actuating lever, comprising a spring associated with each type bar, a movable member pivotable around an axis parallel to the axis of the platen of the typewriter and movable into two positions corresponding respectively to the lower case and upper case positions of the movement, said movable member comprising an elongated U-shaped part having a series of slots on the concave portion thereof, the number of slots being equal to the number of type bars, each of said slots having a series of notches along their edges, each of said springs attached at one of its ends to said actuating levers for each of said type bars and attached at its other end to selected notches in said slots to adjust the tension of the spring and thus adjust the striking force of the type bars, the axis of said movable member being located between the points of attachment of each spring. 

1. An individual adjusting device for the striking force of each type bar of a typewriter acting as a function of the position of the lower case and upper case movement, so as to increase, maintain constant or reduce said striking force, each type bar including an actuating lever, comprising a spring associated with each type bar, a movable member pivotable around an axis parallel to the axis of the platen of the typewriter and movable into two positions corresponding respectively to the lower case and upper case positions of the movement, said movable member comprising an elongated U-shaped part having a series of slots on the concave portion thereof, the number of slots being equal to the number of type bars, each of said slots having a series of notches along their edges, each of said springs attached at one of its ends to said actuating levers for each of said type bars and attached at its other end to selected notches in said slots to adjust the tension of the spring and thus adjust the striking force of the type bars, the axis of said movable member being located between the points of attachment of each spring. 